Method for operating a tachograph and tachograph

Abstract

Data obtained by a tachograph and stored in a memory of the tachograph in a first memory region in a predetermined first data format is processed according to a predetermined processing rule and is stored in a predetermined second data format, which differs from the predetermined first data format, in a second memory region. At least part of the data stored previously in the second memory region is read depending on an inquiry of an external reading unit in relation to the tachograph and is put out via a data interface of the tachograph while maintaining the predetermined second data format.

The invention claimed is: 
     
       1. A method for operating a tachograph comprising:
 conditioning acquired data stored in a first memory region in a predefined first data format according to a predefined conditioning rule; 
 storing the conditioned data in a second memory region in a predefined second data format, the second data format differing from the first data format; 
 reading at least a portion of the data stored in the second memory region as a function of an inquiry from a reading unit, the reading unit arranged externally to the tachograph; 
 outputting the at least a portion of the data stored in the second memory region via a data interface of the tachograph, 
 wherein the predefined second data format of the at least a portion of the data stored in the second memory region is preserved; and 
 updating at least one of an oldest data index indicating an oldest record in the second memory region and a last data index indicating a newest record in the record memory region. 
 
     
     
       2. The method as claimed in  claim 1 , wherein conditioning of the acquired data in accordance with the predefined conditioning rule comprises:
 determination of at least one cryptographic check value as a function of the acquired data. 
 
     
     
       3. The method as claimed in  claim 2 , wherein the at least one cryptographic check value is determined as a signature. 
     
     
       4. The method as claimed in  claim 1 , further comprising operating the second memory region as a first circular buffer. 
     
     
       5. The tachograph as claimed in  claim 1 , further configured to:
 check for a change of day; and 
 the conditioning of the acquired data and storing of the conditioned data includes conditioning of the acquired data for a respectively preceding day and the storing the conditioned data in the predefined second data format in the second memory region after the change of day has been detected.